Quantum computers, which are under development, are based on quantum mechanics and the principle of representing information using quantum properties. This has the potential to massively increase computing power. In this illustration, an electric field (positive and negative poles shown) controls the spin state of electrons (blue) and effectively stretches them. As the current runs through the particles their frequency is changed, which you can observe by microwaves (green) in a phenomenon called ‘stark shift’. Created for the University College of London.